So far we have just show plots based on an X-Y coordinate system.
This is not the only types of graphs you can create with JpGraph.
Another common type is Pie plots. JpGraph supports both 2D and 3D pie
plots. For 2D pie plots there are also 2 versions, but more on that
later.

The main difference as compared to the X-Y plots is that to all pie
plots are added to the
PieGraph() instead of the Graph() object we used for the X-Y graphs
we have drawn so far. For this you must first include the
"jpgraph_pie.php" in your script (or "jpgraph_pie3d.php" if you want to
use 3-dimensional pies).

Below you cane see the code needed to create the simplest possible
pie graph just using the default settings.

Adjust the labels for the slice (color, font, format, position ) by
accessing the value
property of pie plots, for example (
PiePlot::value::SetFont(), You can read more about label formatting
and how to change what is displayed as a value further down in this
chapter.

The next simplest addition we can do is to add a legend to the pie
graph. We do this by using the
SetLegends(); method. By adding the legends to the previous example
we get the following image

(In the figure above we also moved the center of the pie slightly to
the left to make more room for the legend box.)

The text for the legends can also contain printf() style format
strings to format a number. This number passed on into this string is
either the absolute value of the slice or the percentage value. How to
switch between the is describe further down in this chapter.

The next change you might want to change is the size and position of
the Pie plot. You can change the size with a call to
SetSize(); and the position of the center of the pie plot with a
call to SetCenter();
The size can be specified as either an absolute size in pixels or as a
fraction of width/height (whatever is the smallest). The position of
the pie plot is specified as a fraction of the width and height.

To put the size and positioning API to use we will show how to put
several pie plots on the same pie graph. In the following example we
have also adjusted the legends of the slice values to use a smaller
font.

What we do in this example is quite simple, create 4 pie plots, make
them smaller and put them in the four corner of the graph. This will
give the result as shown in the following example.